Don't apologize for anything unless you did something wrong intentionally and genuinely feel bad about doing it (see rule #3). Apologiing for accidents is for pussies and followers.
If you bump into someone and they look pissed off, say "Pardon me" or "Excuse me", but never say "Sorry about that". If they pretend they didn't notice, there's no need to say anything, they know it was an accident and are already over it (or they realize you're bigger than they are and don't want to scrap, which is also fine). If you go for ice in the cocktail sink at the same time as a co-worker and accidentally stab them in the hand with your scoop and they say "Ow!", don't apologize, say "wow, that was careless of me!"
Apologizing for accidents is weak. Apologizing for intentional slights or things you recognize that you did wrong, however, is manly (again, see rule #3).
